The present invention relates generally to millimeter wave integrated circuit structures and more particularly to a balanced mixer incorporating image waveguide components.
Image waveguide transmission line devices consisting of a dielectric waveguide mounted upon a conductive image plane are well known. Additionally, such apparatus has been fabricated into integrated circut devices including active circuit elements in order to implement various types of circuitry. Typical examples of such apparatus is disclosed in U.S. Pat. No. 3,986,153, entitled "Active Millimeter Wave Integrated Circuit", which issued on Oct. 12, 1976, to H. J. Kuno, et al., U.S. Pat. No. 4,006,425, entitled "Dielectric Image Guide Integrated Mixer/Detector Circuit", which issued on Feb. 1, 1977 to Y. W. Chang, et al., and U.S. Pat. No. 3,995,238, entitled "Image Waveguide Transmission Line and Mode Launchers Utilizing Same", which issued on Nov. 30, 1976 to R. M. Knox, et al. The latter reference discloses several types of waveguide transmission line circuits including a mixer circuit and a signal coupler formed by dielectric image waveguide components attached to an image plane by a thin film of plastic.
While such apparatus has proven to be satisfactory for certain millimeter wave applications, prior art practice is inherently deficient in providing a ruggedized structure which exhibits greater efficiency, reliability and performance coupled together with an enhanced fabrication simplicity as well as minimum size, cost and weight.